In New England, fishermen are bracing for what may be unprecedented restrictions, or even a shutdown, of cod fishing in the Gulf of Maine. Federal regulators say new data show cod as dangerously overfished. But fishermen say they don't believe that, and say drastic restrictions would be catastrophic. NPR's Tovia Smith reports.

TOVIA SMITH, BYLINE: Three years ago, scientists found plenty of cod around. After years of overfishing, they said the stock had rebounded. But new data this season shows just the opposite.

RICK CUNNINGHAM: It's highly frustrating because those fish may never actually have existed.

SMITH: Rick Cunningham is chair of the New England Fishery Management Council that will recommend in the next few weeks how much to limit future cod fishing.

CUNNINGHAM: There is going to be no way to avoid pain to the industry. We almost get to a point of having to close the Gulf of Maine.

VITO GIACALONE: Shut the Gulf of Maine cod down, really? It's almost not thinkable. It will be the biggest socioeconomic disaster in the fishery in the Northeast - ever.

SMITH: Vito Giacalone, a fisherman with the Northeast Seafood Coalition, says there's no more important fish than cod in these waters that stretch from Cape Cod up to Canada. It's been the mainstay here for centuries. And because groundfish are all caught together in the same nets, any restriction on cod would also limit the catch of pollock or haddock, for example.

GIACALONE: Without cod, it's over. I would say 120 vessels in this port would end up being insolvent. And that's only the tip of iceberg because then you have the state of New Hampshire - every one of those vessels will be in trouble.

What do you got, Joe?

JOE: Four hundred pounds.

(SOUNDBITE OF BOAT ENGINE)

SMITH: As he greets a 40-foot trawler coming in to offload at Fisherman's Wharf in Gloucester, Giacalone says the new data is just as fishy as the old.

GIACALONE: Which one's wrong? What's to say that this one's not wrong and that one was right? You know, this doesn't pass the red-face test.

SMITH: As his catch is weighed in and iced, fisherman Dave Marciano says cod are as plentiful these days as he's seen in 30 years. He says new rules should not be based on the scientists' doomsday reports.

DAVE MARCIANO: With the fish stocks, they're trying to project out 20 years. How often do you think they're going to be wrong?

PETER SHELLEY: I hope we find out that it's wrong. But I wouldn't bet on that.

SMITH: Peter Shelley, with the Conservation Law Foundation, concedes trying to assess fish stocks is not an exact science.

SHELLEY: I've heard fishery science compared to forestry science, except you have to do it with a blindfold - and the trees keep moving.

SMITH: Shelley says scientists are looking into several different explanations for the disparities between the 2008 and 2011 data. But unless the new reports are totally rejected, he says, fishing restrictions will be mandatory.

SHELLEY: Under the black letter of the law - certainly, as we would read it - you have to cut it back 85 percent. And that's pretty clear.

SMITH: But, Shelley says, there may be some wiggle room, for example, that would allow the restrictions to phase in gradually. Eric Schwab, of the National Oceanic and Atmospheric Administration, says he's also considering ways to mitigate the pain - like just closing certain areas, and letting the smallest boats keep fishing.

ERIC SCHWAB: What we are exploring are some options that would allow us to take a step in the right direction from the perspective of protecting the stock, but perhaps not all the way to the lowest catch limits that this assessment would indicate.

MARCIANO: We're taking the cod out first. Then we'll take the pollock out.

SMITH: Out on the docks, however, fishermen like Dave Marciano are not exactly reassured.

MARCIANO: Only a fool, a liar or a liberal would believe anything that comes out of this (bleep) government.

SMITH: Marciano is one of many still reeling from new fishing rules, implemented last year, that set up a catch-sharing plan, a kind of cap and trade for fishing. He says it's driving small fishermen like him to ruin.

MARCIANO: This ain't even my (bleep) rig. I lost everything I owned after 20 (bleep) years.

SMITH: About a dozen proposals are pending to loosen federal fishing laws, but none will pass in time to help cod fishermen in the Gulf of Maine this season. Lawmakers, meantime, are already working on plans for federal disaster assistance.